9th Grader Arrested, Searched for Building a Clock

A 14-year-old in Dallas, Texas has been arrested for bringing a clock to his school. [Ahmed Mohamed] could be any one of us. He’s a tinkerer, pulling apart scrap appliances and building projects from the parts. He was a member of the his middle school robotics team. The clock was built from a standard four digit seven segment display and a circuit board. [Ahmed] built the circuit inside a Vaultz hard pencil case like this one. He then did what every other experimenter, inventor, hacker, or maker before him has done: He showed off his creation.

Unfortunately for [Ahmed] one of his teachers immediately leapt to the conclusion that this electronic project was a “hoax bomb” of some sort. The police were called, [Ahmed] was pulled out of class and arrested. He was then brought to a detention center where he and his possessions were searched. [Ahmed] is now serving a three-day suspension from school. His clock is considered evidence to be used in a possible criminal case against him.

If this situation doesn’t get your blood boiling, then we don’t know what does. Not only is there a glaring racial issue here, but also an issue of allowing kids to bring their projects to school. We hope you’ll join us in expressing outrage at this whole debacle, as well as supporting [Ahmed] in any way you can. Let’s join together as a community to make sure a few small-minded individuals don’t break the spirit of this budding hardware hacker.

For anyone out there who would like to support [Ahmed]’s education even when his school won’t, [Anil Dash] is will be in contact with the family later today. We’re offering a gift card for the hackaday store and we would assume other contributions would also be welcome. -Ed.

Continue reading “9th Grader Arrested, Searched for Building a Clock”

Demonstrating Science at Harvard University

What if there was a job where you built, serviced, and prepared science demonstrations? This means showing off everything from principles of physics, to electronic theory, to chemistry and biology. Would you grab onto that job with both hands and never let go? That was my reaction when I met [Dan Rosenberg] who is a Science Lecture Demonstrator at Harvard University. He gave me a tour of the Science Center, as well as a behind the scenes look at some of the apparatus he works with and has built.

Continue reading “Demonstrating Science at Harvard University”

Upgrading an Old Camera with a New Light Meter

[Marc] has an old Voigtländer Vito CLR film camera. The camera originally came with an analog light meter built-in. The meter consisted of a type of solar panel hooked up to a coil and a needle. As more light reached the solar panel, the coil became energized more and more, which moved the needle farther and farther. It was a simple way of doing things, but it has a down side. The photo panels stop working over time. That’s why [Marc] decided to build a custom light meter using newer technology.

[Marc] had to work within the confines of the tiny space inside of the camera. He chose to use a LM3914 bar display driver IC as the primary component. This chip can sense an input voltage against a reference voltage and then display the result by illuminating a single LED from a row of ten LEDs.

[Marc] used a photo cell from an old calculator to detect the ambient light. This acts as a current source, but he needed a voltage source. He designed a transimpedence amplifier into his circuit to convert the current into a voltage. The circuit is powered with two 3V coil cell batteries, regulated to 5V. The 5V acts as his reference voltage for the display driver. With that in mind, [Marc] had to amplify this signal further.

It didn’t end there, though. [Marc] discovered that when sampling natural light, the system worked as intended. When he sampled light from incandescent light bulbs, he did not get the expected output. This turned out to be caused by the fact that incandescent lights flicker at a rate of 50/60 Hz. His sensor was picking this up and the sinusoidal output was causing problems in his circuit. He remedied this by adding two filtering capacitors.

The whole circuit fits on a tiny PCB that slides right into position where the original light meter used to be. It’s impressive how perfectly it fits considering everything that is happening in this circuit.

[Thanks Mojay]

Vibrating Distance Torch Illuminates the Dark without Light

If you’ve ever had to move around in a dark room before, you know how frustrating it can be. This is especially true if you are in an unfamiliar place. [Brian] has attempted to help solve this problem by building a vibrating distance sensor that is intuitive to use.

The main circuit is rather simple. An Arduino is hooked up to both an ultrasonic distance sensor and a vibrating motor. The distance sensor uses sound to determine the distance of an object by calculating how long it takes for an emitted sound to return to the sensor. The sensor uses sounds that are above the range of human hearing, so no one in the vicinity will hear it. The Arduino then vibrates a motor quickly if the object is very close, or slowly if it is far away. The whole circuit is powered by a 9V battery.

The real trick to this project is that the entire thing is housed inside of an old flashlight. [Brian] used OpenSCAD to design a custom plastic mount. This mount replaces the flashlight lens and allows the ultrasonic sensor to be secured to the front of the flashlight. The flashlight housing makes the device very intuitive to use. You simply point the flashlight in front of you and press the button. Instead of shining a bright light, the flashlight vibrates to let you know if the way ahead is clear. This way the user can more easily navigate around in the dark without the risk of being seen or waking up people in the area.

This reminds us of project Tacit, which used two of these ultrasonic sensors mounted on a fingerless glove.

A Simple Circuit For Testing Infrared Remote Controls

Every now and then a remote control acts up. Maybe you are trying to change the channel on your television and it’s just not working. A quick way to determine if the remote control is still working is by using a cell phone camera to try to see if the IR LED is still lighting up. That can work sometimes but not always. [Rui] had this problem and he decided to build his own circuit to make it easier to tell if a remote control was having problems.

The circuit uses a Vishay V34836 infrared receiver to pick up the invisible signals that are sent from a remote control. A Microchip 12F683 processes the data and has two main output modes. If the remote control is receiving data continuously, then a green LED lights up to indicate that the remote is functioning properly. If some data is received but not in a continuous stream, then a yellow LED lights up instead. This indicates that the batteries on the remote need to be replaced.

The circuit also includes a red LED as a power indicator as well as RS232 output of the actual received data. The PCB was cut using a milling machine. It’s glued to the top of a dual AAA battery holder, which provides plenty of current to run the circuit.

Adding A Backlight To A Cheap Multimeter

We don’t all need super high quality electronic testing gear. Sometimes second-hand or inexpensive equipment is accurate enough to get the job done. Though it can be a bit annoying to miss out on some of those “luxury” features. [Ekriirke] had this problem with his cheap multimeter. He wished the LCD screen had a backlight for easier visibility, so rather than upgrade to a more expensive unit he just added one himself.

After opening up the multimeter [Ekriirke] found that it ran on a single 12V battery. He realized that the simplest thing to do would be to wire up four white LEDs in series. The four LEDs were arranged within the case off to each side of the LCD, one in each corner. The leads were bent at 90 degree angles and soldered together “dead bug” style. Thin strips of copper foil tape were attached to the PCB in such a way that the anode and cathode from the LEDs would make contact when the case was closed back up.

The tape wraps around to the other side of the PCB where there was more room for the next piece of the circuit. A capacitor, resistor, and transistor are used in conjunction with a momentary switch. This circuit allows [Ekriirke] to turn on the light for about ten seconds by pressing the button one time. The circuit also runs through the meter’s dial switch, preventing the LEDs from being turned on while the meter itself is turned off.

[via Reddit]

Embedding PCBs In 3D Prints

The folks over at Lunchbox Electronics are working on a very cool prototype: embedding LEDs inside standard 1×1 Lego bricks. Being a prototype, they needed a cheap way to produce Lego bricks stuffed with electronics. It turns out a normal 3D printer has okay-enough resolution, but how to put the electronics in the bricks? Gcode wizardry, of course.

3d-printed-LEGO-w-pcb-thumbThe electronics being stuffed into the bricks isn’t much – just a small PCB with an LED. It does, however, need to get inside the brick. This requires stopping the 3D printer at the right layer, moving the print head out of the way, inserting the PCB, and moving the head back to where it stopped.

Gcode to the rescue. By inserting a few lines into the Gcode of the print, the print can be paused, the print head raised and returned, and the print continued.

If you want to check out what these light up Lego look like, There’s a Kickstarter happening now. It’s exactly what the 80s space sets needed, only thirty years late.